Sensors for robotic devices

ABSTRACT

A robotic device having a body with an upper surface resiliently connected to a lower surface and having a bump sensor including a contact point on the lower surface, which contact pint is in its normal position when centrally located within a sensor device, which is an aperture having a conducting inner periphery, which sensor device is located in the upper surface of the robotic device, so that a bump on the upper surface is detected by the robotic device when the contact point abuts the aperture conducting inner periphery. The robotic device also includes a drop sensor for use in association with the lower surface of the robotic device with the lower surface having a periphery around which a plurality of drop sensors are located, with each drop sensor including a body located therein, a movably vertically oriented member, so that when any such member becomes positioned over a drop in terrain, the vertically oriented member will drop downwardly and trigger the production of a signal which is sensed by the robotic device.

TECHNICAL AREA

This invention relates to sensor devices for robotic and autonomousmachines and, in particular, to sensors for determining obstacles andhazards in both the horizontal and vertical.

BACKGROUND TO THE INVENTION

Robotic machines may be used for a number of purposes but for assistanceand easy description of the invention we will consider the machine beingused in association with a self mobile vacuum cleaner.

Such machines have a means to cause them to operate in variousdirections and have a computer system associated therewith whereby themachine can remember which parts of a room it has cleaned and also it isnecessary for the machine to be able to note when it strikes anobstruction, partly to be able to move away from the obstruction at thetime but also so as to avoid the obstruction in the future whilst stillcleaning the remainder of the floor.

The types of obstructions can be both solid obstructions on the floor,such as pieces of furniture, walls or incursions into the room of suchthings as benches or the like and can also be “negative” obstructionssuch as a stair or step down which the machine will fall if not stopped.

As far as the positive instructions are concerned there have previouslybeen proposed various forms of bump sensors or object detection sensorsfor a robotic device however these are usually of a remote sensing type,which are usually IR or RF sensors, and which tend to be associated withcomplicating the electronics of the device and can be quite expensive.

OUTLINE OF THE INVENTION

It is a first object of the invention to provide in a robotic device,bump sensors which are simple in construction but reliable and robust inuse which can control the necessary movement of the device and, at thesame time, provide a required signal to enable the memory of the deviceto navigate it as required.

A second object of the invention is to provide a robot device havingsensors which can identify when the surface upon the robot is movingchanges to prevent the robot, for example, falling down stairs andwhich, again, can give a good indication for future reference to avoidthe problem again.

The invention in a first aspect is a robotic device having a body havingan upper surface resiliently connected to a lower surface and having abump sensor including a contact point on the lower surface which contactpoint is centrally located in its normal position within a sensor devicebeing an aperture having a conducting inner periphery which sensordevice is located in the upper surface such that a bump on the uppersurface is detected by the robotic device when the contact point abutsthe aperture periphery.

It is preferred that the robotic device detect a bump by means of anelectrical signal generated when the contact point touches the sensordevice. It is further preferred that the conducting inner periphery ofthe sensor device consist of a multiplicity of contact points, or switchsegments, so that a computer device within the robotic device, saiddevice having a memory, can determine the location of the bump on therobotic device.

While an electrical contact is the preferment here it is envisaged othersignals such as infrared and pneumatic could be used.

It is also preferred that the upper surface be a plate device whichrests on a plurality of ball transfers affixed to a plate devicecomprising the lower surface. By this means the upper plate is free tomove relatively to the lower plate by a distance equal to the differencein radius of the upper and lower plate. It is therefore preferred thatthe upper plate have a greater diameter than the lower plate.

It is further preferred that the upper and lower surfaces each belocated within housings such that the entire unit comprises the body ofthe robotic device. It is also preferred that the upper plate be rigidlyconnected to its housing while the lower plate is attached to a drivemechanism which includes a locomotion means such as wheels.

The invention in a second aspect is a drop sensor for use in associationwith a lower surface of a robotic device, said lower surface having aperiphery around which a plurality of such drop sensors are located,each drop sensor including a body having moveably located therein avertically oriented member such that when any such member becomespositioned over a drop in terrain the vertically oriented member willdrop down and trigger the production of a signal which is sensed by therobotic device.

It is preferred that the signal is an interruption to the passage oflight between at least one LED and receptor. The signal used however maybe of any kind which is considered appropriate alternatively anyswitching system desired could be used.

It is preferred that the signal cause the robotic device to changedirection away from the drop.

It is also preferred that the vertically oriented members used in thedrop sensors take the form of rods. It is further preferred that theserods be able to resume their original positions within the drop sensorsonce the robotic device has returned to substantially level terrain.

The rods may preferably comprise armatures of solenoids and on operationof the solenoid the rods are caused to be raised. While this method ispreferred it is envisaged that any retraction method, includingpneumatic means may be used.

In order that the invention may be more readily understood we shalldescribe by way of non limiting embodiment a robotic device whichincorporates both aspects of the invention therein with reference to theaccompanying drawings.

BRIEF OUTLINE OF THE DRAWING FIGURES

FIG. 1 shows a schematic drawing of the interior of a robotic device;

FIG. 2 shows an upper view of the interior of a robotic device;

FIGS. 3,4 and 5 show the components of the bump sensor of the invention;

FIG. 6 shows a cross-section through the components of the bump sensor;

FIG. 7 shows the drop sensor of the invention in its lowered state;

FIG. 8 shows the drop sensor in the raised position;

FIG. 1 shows the interior of a robotically controlled cleaning device 10having an upper surface or plate 11, in which the bump sensor 20 isshown (FIG. 2),. Drop sensors 30 are shown arranged around the lowerperiphery of the lower surface or plate 12.

In its complete form the cleaning device has a body which includes achassis and drive wheels.

The robotic device has an outer shell rigidly attached to the upperplate 11. The upper plate rests on multiple transfer balls that areaffixed to the lower plate 12 and these plates are able to move relativeto one another whilst supported by these transfer balls. The upper platehas a greater diameter than the lower plate and is able to moverelatively to by a distance equal to the difference between the radii ofthe two plates when the robotic device is bumped.

There are also provided spring means which keep the upper plate centeredover the lower plate when no contact is made between an object and theouter shell of the robotic device.

The bump sensor 20 which detects any bump activity includes a contactmember 21 mounted fixedly on lower plate 12 and extending throughaperture 23 in upper plate 11. The periphery of this aperture issurrounded by conducting segments 22 each of which is identifiable by acomputer device associated with the robotic device.

The arrangement is such that movement of the upper plate 11 caused bythe robotic device hitting some object causes the contact member 21 tohit one of the conducting segments 22 and a signal to be generated whichthe robotic device's computer recognizes and permits the location of thebump to be identified

Subsequent to encountering an impediment to movement the actual movementof the device can be controlled by software however various modes ofmovement can be used.

If required, the software associated with the device can map theposition of an obstacle in memory.

It will be seen that the device can if required move in a more or lessrandom appearing manner throughout the room and, if associated with avacuum cleaner, the vacuum cleaner will effectively clean the room as itpasses over an area.

The walls of the room would provide an obstruction and if a wall isstruck effectively head on then after the machine is reversed somewhatand again commences to move this movement will tend to be parallel tothe wall.

In another arrangement the robotic device can strike a wall, rotatethrough 90°, move along the wall a distance half its diameter, turnagain through 90° and proceed back across a floor thereby systematicallycleaning it if the robotic device is a cleaning robot.

Clearly any range of movement can be programmed into such a device, itis unique however in terms of the use of the bump sensor. It can be seenthat the bump sensor of the device is basically simple, we find it quitesatisfactory to use only four (4) segments but if it was required agreater number than this, preferably eight (8) but possibly six (6)could be used, the more sensors which are used the more delicate themanoeuvring can be to cover the area as quickly as possible.

In the second aspect of the invention we provide drop sensors 30 asshown in FIGS. 7 and 8 to ensure that the device does not “fall” downstairs or, say a step in the middle of a split level room.

There may be four (4) such sensors, although if required there could bemore, and these each comprise a rod member 32 mounted for verticalmovement within a body 33 of the device which rod members may have arounded lower end or preferably a ball 36 of a relatively low frictionmaterial, such as nylon attached to their lower ends. In the embodimentof the invention shown the lower part of the rod member, adjacent ball36, consists of a tightly wound coil 37 to lend flexibility to this partof the drop sensor.

The rods themselves are preferably of iron or steel and pass upwardlythrough the windings of solenoid.

Also are two pairs 34 of LED's and two phototransistors 35 thearrangement being such that when the robotic device is moving over eventerrain and the rod member 32 is in its elevated position (FIG. 8) afirst LED/receptor pair is occluded while light transfer is continuousacross a second pair. Should the drop sensor pass over a stair or otherchange in terrain the rod member falls to the position shown in FIG. 7and the second LED/receptor pair becomes occluded while the first opens.It is not pertinent which pair is which however this approach provides asimple means of determining when a drop has been reached as a signal issent to the device's computer.

When the computer receives the signal it can stop the robot and thesolenoid becomes energised and causes the rod member 32 to be retractedthereby passing the LED/receptor pairs to be returned to their originalstate. The robotic device meanwhile will know that it is free to moveaway from the step.

Once the movement of the device is stopped, the solenoid is energised sothat the rod and the ball are raised to no longer extend below the levelof the device, the drive motors are commenced to cause the device tomove at 180° to its initial movement until the device will have clearedthe edge of the step, the solenoids can then be released and the rod orrod members dropped into contact with the surface, the drive wheels aremanipulated to turn the device through a pre-determined angle and thenit commences to move along that line.

If, say, this movement is not such as to cause it to move away from thestep or the like then it is possible that one of the rods on the side ofthe device will pass over the edge, the operation is repeated, theforward movement is stopped, the rod is raised by operation of thesolenoid, the device moves rearwardly by a distance sufficient to ensurethat it has cleared the step, it is caused to rotate through apre-determined angle, the solenoid can be released so that the rod comesinto contact with the ground and forward movement is again effected.

Again, should this be required, the operating computer of the system cannote where the rod dropped over the edge so as to avoid contact with theedge during further movement.

It will be seen that the sensors provided in this way are basically verysimple, the solenoid permits the sensor to be removed from anylikelihood of contact with the edge of the obstruction and the movementof the device is relatively rapidly reestablished and the cleaning,assuming it be a vacuum cleaner, continued.

Whilst in this specification we have described two aspects of theinvention it will be appreciated that they both effect the samefunction, although under different circumstances.

The bump sensors operate when the shell of the device contacts anobstruction, the segmented switch is caused to move relative to the mainchassis of the device, electrical contact is made and once this occurs,the remainder of the operation occurs automatically.

The stair sensitive rods cause effectively an identical operation ifthey drop downwardly, as when they pass over the edge of a step, theonly difference being the additional step of causing the rod members torise by use of a solenoid so that they clear a drop before the roboticdevice moves.

Whilst simple sensors for providing information concerning variousobstacles to a robotic device have been described herein it is envisagedthat these could be distributed around the machine as desired and thatany modification in their mechanical arrangement will not depart fromthe scope of the invention.

1. A robotic device, comprising: a lower surface; means for producing asignal detectable by said robotic device; and, a plurality of dropsensors located around a periphery of said lower surface, each dropsensor of said plurality of drop sensors comprising a body having avertically oriented member movably located within said body, so that anysaid vertically oriented member of any said drop sensor of saidplurality of drop sensors becomes positioned over a drop in terrain,said vertically oriented will drop downwardly from a first position to asecond position to trigger, in said second position, said means forproducing a signal detectable by said robotic device.
 2. The roboticdevice according to claim 1, wherein said means for producing a signaldetectable by said robotic device is a signal caused via an interruptionto a light beam between at least one LED and one LED receptor.
 3. Therobotic device according to claim 1, wherein said vertically orientedmember of each said drop sensor is a rod member.
 4. The robotic deviceaccording to claim 3, further comprising means for permitting each saidrod member to resume its said first position within said drop sensor,means for signalling said robotic device to return to substantiallylevel terrain and means for returning said robotic device tosubstantially level terrain.
 5. The robotic device according to claim 4,wherein said means for returning said robotic device to substantiallylevel terrain comprises a solenoid.
 6. The robotic device according toclaim 4, wherein said means for returning said robotic device tosubstantially level terrain comprises a pneumatic device.
 7. A roboticdevice, comprising: a body having an upper surface and a lower surface,said upper surface being resiliently connected to said lower surface andhaving a bump sensor with a contact point on said lower surface; a firstsensor device located in said upper surface and being an aperture havinga conducting inner periphery, with said contact point of said bumpsensor being in a normal position centrally located within said firstsensor device, so that a bump on said upper surface is detectable bysaid robotic device when said contact point of said bump sensor abutssaid conducting inner periphery of the aperture of said first sensordevice; means for producing a signal detectable by said robotic device;and, a second sensor device comprising a plurality of drop sensorslocated around a periphery of said lower surface, each drop sensor ofsaid plurality of drop sensors comprising a body having a verticallyoriented member movably located within said body, so that any saidvertically oriented member of any said drop sensor of said plurality ofdrop sensors becomes positioned over a drop in terrain, said verticallyoriented will drop downwardly from a first position to a second positionto trigger, in said second position, said means for producing a signaldetectable by said robotic device.
 8. The robotic device according toclaim 7, further comprising means for generating an electrical signalwhen said contact point touches said first sensor device for detecting abump on said upper surface.
 9. The robotic device according to claim 7,wherein said conducting inner periphery of said first sensor deviceincludes a plurality of contact points for determining a location of abump against said robotic device.
 10. The robotic device according toclaim 9, wherein said plurality of contact points is a plurality ofswitch segments.
 11. The robotic device according to claim 7, furthercomprising means for moving said upper surface relative to said lowersurface.
 12. The robotic device according to claim 7, wherein said uppersurface is a first plate resting on a plurality of ball transfersaffixed to a second plate comprising said lower surface.
 13. The roboticdevice according to claim 12, wherein said first plate is movablerelative to said second plate by a distance equal to any difference inradius of said first plate and of said second plate.
 14. The roboticdevice according to claim 7, further comprising a housing having agreater diameter than said lower surface with, at least, said uppersurface being located within said housing.
 15. The robotic deviceaccording to claim 7, further comprising a drive mechanism having meansfor locomotion, with said lower surface being attached to said drivemechanism and able to move via said means for locomotion.